Glacier and climate evolution in the Pariacacá Mountains, Peru

Glaciers in Peru play a major role in water availability and they also have direct implications on natural hazards such as glacial lake outburst floods (GLOFs) and/or ice avalanches, which have caused a high number of fatalities and damage to infrastructure in the last decades. Despite a noticeable effort to quantify and understand the shrinking and thawing of glaciers in Peru, there are still regions where detailed assessment is still missing. In this work, a set of remote sensing images were used to map, for the first time, the evolution of the glaciated area (from 1970 to 2018) in the Pariacaca Mountains (11o5’ S, 76o0’ W) in the Cordillera Central of Peru. The results evidenced a marked decrease of the glaciated surface, with 55.3% shrinkage since 1970 and 40% since 1987. Faster glacier retreat occurred between 1985 and the end of the 1990s, and this period was followed by a significant slowdown in shrinking rates. The differential loss of ice, depending on elevation and exposure to incoming radiation, has led to changes in spatial distribution of the glaciers. Currently, they have almost completely thawed below 5000 m a.s.l. They are mostly located in south- to west-facing aspects. Ice melting in the last decades has even affected the summit areas. Finally, the development of ablation hollows has been identified as an important driver of glacier thaw. These features are formed mainly in gentle slopes and highly irradiated zones between 5000 and 5400 m a.s.l.